Fuel injection pump



March 12,1935. F. w. STOCKMEYER 1,993,759

' FUEL INJECTION PUMP Filed May 24, 1953 Patented Mar. 12, 1 935 FUEL INJECTION PUMP Friedrich Wilhelm Stockmeyer,

Stuttgart, Germany, assignor to Robert Bosch Aktiengesellschaft, Stuttgart, Germany I Application May 24, 1933,

In Germany 9 Claims.

This invention relates to fuel injection pumps for internal combustion engines, and particularly to such pumps capable of providing two injection periods, first pre-injection and then the main injection.

An object of the invention is to simplify the construction of such pumps.

The accompanying drawing,'in vertical section, illustrates the pump at its outer dead center position. The pump housing 0. contains the cylinder b with its piston c. The radial return port (I and suction port e terminate in the annular passage f, to which the fuel inlet pipe L is connected.v A pressure valve 9 and nipple h are arranged axially of the cylinder at its upper end and are connected to the fuel outlet pipe i which leads to an injection nozzle (not shown).

The piston c is provided with an integral control member 70 having the groove q, the edge m curved for a part of its length, and the stem 'n.v

reduced in diameter to form the annular passage p which is thus in continual communication with the fuel chamber 1". The radial bore 3 has a portion of small diameter, and also a portion of larger diameter containing a piston t which is controlled by aspring u bearing against the piston and the screw plug 1 The pin w limits the backward movement of the piston t, which is displaceable against the spring at a pressure less than that required to open the valve 9, and which, upon such displacement, forms a storage chamber :c in bore s.

The operation of the pump is as follows: In the position shown, which is at the beginning of the upward or pressure stroke of the piston c,

the ports d and e are open and the duct s is closed. I

At the beginning of the pressure stroke, fuel from chamber 1- is forced through ports d and 6 until they are entirely covered by control member k. Upon further upward'movement of the piston, the pressure valve 9 is forced off its seat and the pro-injection of the fuel from chamber r starts. This pre-injection then continues until rim m begins to uncover port s, whereupon the pressure of the fuel in chamber? is applied to piston t, causing it to recede. The fuel pressure is thereby decreased sufliciently for valve 9 to close. This then ends the pre-injection period, but after chamber a: is filled, the fuel pressure again rises,

as a result of the further upward movement of piston 0, until valve g is again forced open. The main injection period then starts and it continues until the port 01 is uncovered at the rim m of the control member. Valve y then closes as a result of the reduced fuel pressure and piston t is moved Serial No. 672,535 June 21, 1932 the spring w to the position shown. The fuel continues to be forced out of chamber r through port 12 until the its pressure stroke.

from pipe L into chamb piston reaches the extreme top of During the downward orsuc'tion stroke to the position shown, fuel is drawn 5 er 1', again filling it as well as the passages f, p and q.

The movement of the piston between the end of the pre-injection and the beginning of the main injection periods m the tension of the spring ay be varied by varying 1;-, and also by varying the volume of storage chamber a: by screwing plug 12 in or out.

At the extreme inner position of plug 1;, the two periods are merged into one, and at its extreme outer position the two periods are most widely separated.

gle pumps may be rea In this way, many sin-.

dily connected for multiple Also, by

using different control members, the contour of rim m may be such as to vary the amount of the period of pre-injection relatively to the main injection so as to conform any engine.

In the well known way,

be regulated by turning pis to the load condition of the fuel supply may also ton p with its control member It to any circumferential position desired by means of the rack 11/ and pinion a.

In the example'shown in over pro-injection extends the drawing, however, the entire controlling or governing range of the pump in the same positions of the piston b the inner end face of the -injection, and that part of the end of the pre-injecbeginning of the pre the rim mdetermining tion, are parallel to each to the axis of the piston.

It is obvious that the ecause both the rim of piston controlling the other in planes normal control member 7c need' not be mounted on or form an integral part of the piston, as shown in be separate ently thereof.

What is claimed is:.

a piston in said fuel 0 a storage chamber, and a con the drawing, but may d therefrom and operated independfor internal combushaving a return port,

trol member on the piston constructed and adapted to connect the port and the storage chamber to the fuel chamber.

engines, a fuel chamber 2. In an injection pump for internal combustion having a return port, a

with the fuel chamber and having one end of such shape that the fuel chamber is put into communication with the port at a predetermined point at the stroke of the piston.

3. In an injection pump for internal combustion engines, a fuel chamber having a supply port, a piston, the pump containing a storage chamber, and a control member constructed and arranged to automatically connect the storage chamber to the fuel chamber when the port is closed at a point in the pressure stroke of said piston subsequent to the beginning of the affective discharge stroke thereof.

4. In an injection pump for internal combustion engines, a fuel chamber having a supply port a piston, the pump containing a pressure storage chamber having an adjustable volume, and a positively actuated control member constructed and arranged to automatically connect the storage chamber to the fuel chamber when the port is closed at a predetermined point in the pressure stroke of said piston.

5. In an injection pump for internal combustion engines, a fuel chamber, a piston, the pump having a storage chamber connected thereto, and a control member constructed and arranged to automatically close the connection between the storage chamber and the fuel chamber during the initial portion of the pressure stroke of said piston and to open the connection thereafter, the storage chamber havinga variable volume with an ad- J'ustable maximum value.

6. In an injection pump for internal combustion engines, a fuel chamber having a return port, and an integral piston and control member, said pump containing a storage chamber, and said control member being constructed and arranged to connect the storage chamber to the fuel chamber when the port is closed at a predetermined point in the pressure stroke of said piston.

7. A fuel pump for supplying fuel to internal combustion engines including means for interrupting the delivery of fuel from said pump after a part of the injection for a given cycle has been effected, said means including a pressure storage chamber having a passage connected with said pump, automatic means to close said passage during the early portion of the delivery period of said pump, automatic means to open said passage, whereby said interruption is effected until the pressure in said chamber is raised to the pump discharge pressure.

8. In an injection pump for internal combustion engines, a pump chamber, a reciprocating pumping member, an outlet pipe leading to an injection nozzle, and a storage chamber, control means automatically connecting the pump chamber and the storage chamber after a part of the effective delivery stroke of said pumping member, so that the eilective delivery to the injection nozzle is interrupted until the storage chamber is filled up to a pressure overcoming the resistances in the outlet pipe and nozzle, and means for releasing the pressure in the storage chamber when the effective delivery stroke has ceased.

9. In an injection pump for internal combustion engines having a pump chamber, a reciprocating pumping member, an inlet, an outlet valve normally under closing pressure, and a storage chamber, a control means carried by the pumping member automatically connecting the pump chamber and the storage chamber constructed and arranged so that the effective delivery through the outlet valve is initiated and then interrupted until the storage chamber is filled up to a pressure overcoming the pressure on the outlet valve, and a return port connected to said inlet for releasing the pressure in the storage chamber when the effective delivery stroke has ceased.

FRIEDRICH WILHELM STOCKMEYIER. 

